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<A NAME="CHDCDDFI"></A><h1>About DDE</h1>
<A NAME="TI2998"></A><p>Dynamic Data Exchange (DDE) makes it possible for two Windows applications
to communicate with each other by sending and receiving commands
and data. Using DDE, the applications can share data, execute commands
remotely, and check error conditions.</p>
<A NAME="TI2999"></A><p>PowerBuilder supports DDE by providing PowerScript events
and functions that enable a PowerBuilder application to send messages
to other DDE-supporting applications and to respond to DDE requests
from other DDE applications.</p>
<A NAME="TI3000"></A><h4>Clients and servers </h4>
<A NAME="TI3001"></A><p>A DDE-supporting application can act as either a client or
a server.</p>
<p><img src="images/note.gif" width=17 height=17 border=0 align="bottom" alt="Note"> <span class=shaded>About the terminology</span> <A NAME="TI3002"></A>Used in connection with DDE, these terms are not related to <i>client/server architecture,</i> in
which a PC or workstation client communicates with a database server.</p>
<A NAME="TI3003"></A><p>A <strong>client</strong> application makes requests
of another DDE-supporting application (called the server). The requests
can be commands (such as <b>open</b>, <b>close</b>,
or <b>save</b>) or requests for data.</p>
<A NAME="TI3004"></A><p>A <strong>server</strong> application is the opposite
of a client application. It responds to requests from another DDE-supporting
application (called the client). As with client applications, the
requests can be commands or requests for specific data.</p>
<A NAME="TI3005"></A><p>A PowerBuilder application can function as a DDE client or
as a DDE server.</p>
<A NAME="TI3006"></A><p>In PowerBuilder, DDE clients and servers call built-in functions
and process events. DDE events occur when a command or data is sent
from a client to a server (or from a server to a client).</p>

